heavier

I own a Stevens model 200, in .25-06 and it has a 22" sporter barrel. I've been reloading for it, using light weight varmint bullets and moderate loads. It will produce 5/8" groups at 100 yards and 1 1/4" groups at 200 yards. I'd like to see 1 hole groups at 100 and 1/2" groups at 200...